Compressor for refrigerating apparatus



Oct. 27, 1942 R. N. FslcH-r COIPRESSOR FOR REPYRGERATING APPARATUS `1mm Feb. 2 6, 1938 a sheets-sheet 1 ATTORNEY s 0d# 27, 1942- R. N. FEICHT 2,299,811

I COMPRESSOR FOR REFRGERATING APPARATUS Filed Feb. 2e, 19:58 a sheets-smet 2 l i Z] nyvsgok.

Mw 3b ATTORNEYS Oct. 27, 1942.

R; N. FElcHT f 2,299,811

COMPRESSOR FOR REFRIGERATING APPARATUS l Filed Feb. 26, 1938 8 Sheets-Shet 5 /44 num f@ m|\\\ www; fo M- M :mn l w\ Mz /SZ M /X L /zf /fz "Z /f l z/a [48 ISO 94 84 /o y asf "l'lw 'f w-w/ f; ,26 78 y|l|||||||f| ,64 z I.

\\ A a, y M Nh f/z f/ #a "a ATTORNEYS 4%. v QNVEOR..

BY MZMmm// a 'f/ o 'i 0/ /WI Qct. 27, 1942. R. NfFElcH'r 2,299,811

- l COMPRESSOR -FOR REFRIGERATING APPARATUS VFiled Feb. 2e, 193s a sheets-sheet e 22.4 zzz IAZVE 0R. #zyn N ATTORNEYS Vom. 27, 1942.

R. N. Flalcl-rrA l S t e D.. P A PWS 3 N9 Oct. 27,I 1942. R. N. vr-'lslczl-rr 2,299,811 A COMPRESSOR FOR REFRIGEHATING APPARATUS Filed Feb. 26, 1938 a'sneets-sheet 8 i ATTORNEYS evaporated refrigerant in tem more eflcient.

Patented Oct. 27, `1942 UNITED Ns'rriras APlrrlrN'r OFFICE COMPRESSOR FOR REFRIGRATIN G APPARATUS Robert N. Feicht, Dayton, hio,vassignorlt0 Gen eral Motors Corporation, Dayton, Ohio, a corporation of Delaware 4Appliance February 26, 193s, seria1No.192,ls4e

` r1 Claim.

y panding the refrigerant from the condenser directly in a single stage into the evaporator where the refrigerant evaporates at the low back pressure and all the evaporated refrigerant must-be returned to the condenser by the compressor which must overcome the relatively large pressure diiferential between the evaporator pressure and condenser pressure. l

It is an object of my invention to reduce the pressure ofthe refrigerant passing from the condenser to the evaporator in stages and to Withdraw the evaporated refrigerant at one or more intermediate stages and to use a compressor capable of taking full Vadvantage of the added-eiliciency obtainable from this higher back `pressure order to make the `sysan improved multiple effectrotary compressor in which a means Aoperated by the drive shaft is 1 employed to control the admission of refrigerant through the Jsuction ports ofthe compressor.

It is another object of my invention to provide an improved oiling system for rotary compressors in `which the oil is elevated upon the inside of. the

It is another object of my invention to provide an `improved multiple effect compressor capable of operating with great efliciency while drawing gas at two different back pressures.

It is another object of my invention to provide having'a high volumetric efficiency. l

It isv still another object of my inventionto' provide a multiple effect rotaryl compressor which requiresv no check valves in the Isuction lines.

It is still another object of my invention to provide an improved multiple effect rotary compresser inwhich the ininpeller covers,v uncovers and separates the suction ports so as to properly control the admission of gas througheach of the ports in order to secure the highest leiliciency without the use of any other valves.

It isanother object of my invention to provide drive shaft as Well as theoutside. l

Further objects and advantages of the ,presen invention'will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is lclearly shown.

' In the drawings:

Figrl is a diagrammatic View of a refrigerating system embodying my invention;

Fig. 2 is a sectional View of the compressor shown in'Fig. 1 takenalong the lineA 2 2 of Fig.5; i

Fig. 3 is a sectional view of the compressor proper looking downwardlyvdirectly upon the cylinder block and impeller. The impeller` is shown in'a position to begin to vopen the high pressure suction Air1let';`; ort to permit the admission' of the high pressure gas into the compression chamber;

FFig. 4 is a View similar to Fig. 3 with the impeller located so as to show the end of -the open rperiod of the highpressure port;

Fig.` 5 is a `view similar to Figs. 3 and 4 showing the impeller in position to begin a new suction stroke;

Fig'. 6 is a sectional view of the compressor proper taken along the lines 6-6 of Fig. 5;

Fig. 'l isa sectional view. taken along the lines )1 -1 of Fig. 4;

an improved multiple effect rotary compressor Fig. 8 is a sectional View takenalong the lines 8 8 of Fig. 4; y

Fig. 9, is a sectional View taken along the lines 9--9'of Fig. 5; Fig. 10 is a sectional view takenalong. the lines |0--I0 of Fig.3;

Fig. 11 is asectional viewof a `I2lzof1Fig.v11;. t t Fig. 13 is a horizontal sectional view of a modified form of multiple effectv rotary compressor.

liquidand gas separator shown `between the two restrictors"inv Fig. Ltaken along the lines ll-II of Fig. 12; f'

Fig. 12 1s a sectional view taken along thelines The impeller is shown in position to Abegin the compression stroke;

Fig. 14 is a view similar to Fig. 13 in which the impeller is at the point of beginning to open the high pressure suction port;

Fig. 15 is a view similar to Figs. 13 and 14 in which the impeller has fully opened the high pressure suction port;

Fig. 16 is a view similar to Figs.` 13, 14 and 15 in which the impeller is at the point of closing the high pressure suction port;

Fig. 17 is a sectional view taken along the lines I'I-IT of Fig. 15;

Fig. 18 is a sectional view of another modified form of multiple eiect rotary compressor provided with a roller type impeller, the impeller being shown in position of uncovering the highA pressure suction port; y

Fig. 19 is a sectional view similar to Fig. 18 in which the impeller is shown closing the high pressure suction port;

Fig. 20 is a sectional view taken along the lines 2li-20 of Fig. 18;

Fig. 21 is a horizontal sectional view of another vmodified form of multiple effect rotary compressor with a roller type impeller shown in position just after the beginning of the compression stroke with the impeller at the point of uncovering the high pressure suction port;

Fig. 22 is a horizontal sectional view similar to Fig. 21 with the impeller shown at the point of closing the high pressure suction port;

Fig. 23 is a horizontal sectional view similar to Figs. 21 and 22 in which the impeller is shown in position fully uncovering the -high pressure suction port; and

Fig. 24 is a sectional view taken along the linesV 24-24 of Fig. 23.

BrieyI have shown in Fig. 1 a refrigerating -system comprising a multiple effect rotary comevaporated refrigerant from the separator to the high 'pressure suction inlet of the compressor. The remainder of the liquid refrigerant passes from the bottom of the separator through a second restrictor embodied in the heat exchange de vice and connected to the evaporator. The evapy oratedrefrigerant isgwithd'rawn from the evaporator through a second suction line which passes in heat exchange relationship with the second restrictor and connects to the low pressure inle of the multiple eectcompressor. l

In Figs. 2 to 10 inclusive are shown one form of a multiple. eifect compressor in'which the roller is keyed tothe eccentric shaft in order to'form an impeller of the fixed eccentric type. A slot is cut into the impeller which is employed to register with the high pressure suction inlet port and a second part is providedleading to the compression chamber when the impeller has moved to position where it covers the low pressure inlet port located near the divider block. These ports remain registered for about a sixth of a revolutio'n during which timel the impeller and the divider block always separate the high and low pressure .ports so as to prevent any gas from the high pressure inlet port from being passed back into the low pressure inlet port.

In Figs. 13 to 17.a similar compressor is shown more or less diagrammatically in which the high pressure suction inlet port communicates directly with a port in the impeller which opens directly into the compression chamber.

In Figs. 18 to 20 the impeller is formed of a roller upon the eccentric and only a single high.

suction pressure port is employed in the casing of the compressor.` This port is located so that it opens slightly before the low pressure suction inlet is covered and closes after compression is begun so that it is deemed advisable to provide each port with a check valve.

In Figs. 2l to 24 inclusive there is shown a compressor very similar to that shown in Figs. 18 to 20, including a roller impeller mounted upon an eccentric, but in this form a high pressure inlet port is located and so shaped that no check valves are necessary.- In this form the low pressure inlet port is covered and the high 'pressure inlet port is uncovered and again covered before one-half of the compression stroke is completed.

Referring now more particularly to the drawings and particularly to Fig. 1, there is shown a multiple eect' compressor 30 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser 32 -where the compressed refrigerant is liquefied and forwarded to a restrictor 34 which contains an elongated oriiice. The other end of the restrictor 34 is connected to a liquid and gas separator 36 which is better shown in Figs. 11 and 12. This separator vincludes a cylinder 38 plugged by a plug 40 at its upper end and a plug 42 at its lower end. Within the. cylinder is a vertical pin 44 upon which are mounted baiiies 46 which are separated by spacers 48. The restrictortube 34 extends through the upper two bale members. The baille mem' bers are staggered so that the liquid will pass downwardly at a relatively slow rate over the various bailies to the bottom of the separator. In this separator the liquid has an ample opportunity to evaporate and this evaporation cools the remainder of the liquid down to a temperature corresponding to the pressure which may be kept within the separator.

'I'his pressure within the separator is kept at a relatively low figure by a high pressure suction conduit 50 which extends out of the upper plug 40 of the separator 36 into heat exchange relationship with the restrictor 34 ina heat exchange de;

. vice 52 which is shown diagrammmatically. The

heat exchange device 52 is shown as a container 4 containing a heat transfer liquid and having the restrictor tube 34 and the high pressure suction tube 50 traversing from top to bottom. However,

' any other suitable form of direct or indirect heat exchange device may be employed. Preferably the heat exchangeA between vthese two tubes should be arranged in the best countertlow fashion in order to obtain the greatest eiiiciency from ,f

ing portion.

56. The refrigerant evaporates within the evap- 1 tor tube 54 in the heat exchange means 60, which may be of any suitable direct or indirect type, preferably one which is arranged in counter-flow fashion. This low pressure suction conduit after leaving the heat exchange device 60 passes through insulating means 62 which also surrounds the separator 36 and the lower portion of the heat exchange device y52. The heat exchange device 60 aswell as the evaporating .means .56, is exposed to the medium to be cooled found `within the enclosure 64 indicated diagrammatically.

. The low pressure suction conduit is insulated all exchange vrelationship with the evaporating means 56.

By employing this system with the separator between the two restrictors and by employing a.

multiple effect compressor with a high pressure.

screen ||6 is held in place by a muiiier ||8 which covers the remainder'of the bottom of the compressor and receives the gas from the compressor outlet. The aperture I4 in the bottom plate H2 is located below the oil level within the sealed unit 30, and in order to lubricate the bearings 86 and 88 a pin I 20 is set inside of a threaded aperinlet port connected to withdraw evaporated refrigerant from the separator, the refrigerant used for cooling the liquid supply to the evaporating means is removed at a relatively high back pressure so that a saving in eillciency of as much as can be had. This saving in elciency varies, of course, with the refrigerant used. The savingis further increased by the exchange shown.

` Motor-*compressor unit use ofthe dual heat Referring now'more particularly to Figs. 2 to' shaped housing member 16. Pressed into 'the upper housing member 10 is a cup-shaped motor turevn the eccentric 88. The lower end of this pin is slotted and receives a cotter-pin |22 which is lodged within a slot provided in the bottom plate`||2. The provision of the pin |20 Within the threaded aperture in the eccentric 98 carries the oilupwardly until it reaches an outlet |24 which conducts the oil to the oil groove |26 provided upon the outside of the shaft 96. -This oil groove |26 carries th oil upwardly to the space between the bearings 86 and 88 and a second oil groove |28 is provided for carrying the oil up to the bearing 88.

The cylinder blockv|06 is provided with a low pressure suction inlet |30 extending radially inwardly next to the divider block |32 which is provided within a slot inthe wall of the cylinder block |06. The divider block |32 is kept pressed against the outer surface of the impeller member |04 by a two-compression ltype coil spring |34 which is anchored at the outer end by a bracket |88 fastened by the cap-screw threaded into the member 18. The electric motor operates `to rotate the shaft 96 and the impeller |04 in a clockwise direction as viewed lin Figs. 3, 4`and 5.

Operation ofV first. form of compressor tion inlet |30 is beginning to be drawn into the space designated by the reference character located between the divider block, the portion of frame member 18 having` a rim portion 80 which fits into the housing member 10, a centralbearing portion 84 containing a lower bearing 86 and an upper bearing 88, and a web portion 82 which connects the rim portion 80 with the central bear- The rim portion 80 of the frame member 18 carries the stator 80 of an electric motor', preferably of the split phase or capacitor start induc. tion motor, which has a rotor 92 mounted upon a thimble `member 84 which surrounds the bearing 88 and is pressed onto the upper end of the eccentric ber which includes the eccentric 88 as well as member L04. These two members rotate around within the cylinder wall |06 of the compressor.

This cylinder wall is fastened by means of screws |08 and pins I|0, to a lower finished surface of the metal web or flange surrounding the bearing .86. The'screws |08 also serve to fasten thebottom plate ||2 to the cylinder |06.

'y The bottom plate ||2 is provided with a centrol aperture ||4 covered by. a screen Ill. This the cylinder wall around the low pressure suction inlet |30 and the adjacent wall of the impeller member |04. As the impeller moves further in a clockwise direction, this space grows in size until it includes the entire space between the impeller member |04 and the cylinder. block |06 as shown in Fig. 5. It will be seen thatin Fig. 5 the inlet port is almost covered by the impeller member |04. This position therefore shows that a fullcharge of gas has been drawn into the compressor and that further movement to the `position lshown in Fig. 3 will cause the closing of the -suction inlet port` |30 and the beginning of compression.

In order to use this same compressor for .pump-` ing' the gas from the'separator, the high pressure suction line is connected to a fitting |44 which is threaded into the side of the cylinder block almost opposite the low pressure inlet port |30. This threaded fitting |44 leads to a downwardly extending passage |46 in the cylinder yblock |06 and this passagel46 connects with a passage |48 extending generally radially inwardly and connecting Lwith a short upwardly extending passage |50. This upwardly extending passage |50 ends up in a port provided in the upper surface of the bottom plate ||2 uponwhich the impeller .i member |04 rests. This port |50 is so located that it is at all times within .the confines of the impeller member |04. The impeller member |04, however,

is provided with a slot |52 in the form of an arc which is adapted to register with the port |50.

the position shown in Fig. 3. The remaining portion is covered at lall times by the impeller member "|04," but a portion thereof will register with the slot |52 between the positions of the impeller shown in Figs. 4 and 5.

It will be seen that when the impeller'is in the position shown in Fig. 5 in whichthe low pressure in port |30 is not fully covered, the slot` |52 is not in registration with either the port |50 or the depression |54. A portion of the depression |54 is uncovered but is @not connected' either with the slot |52 or port |50 in any way whatsoever. However, as soon as the impeller moves a few degrees further in a clockwise direction the slot |52 begins to extend over a portion of the depression |54. This, however, merely allows communication betweenv the slot |52` and the compression chamber which is, of course, located between the impeller |04 andthe cylinder block 06. However, as soon as the slot |52 reaches the nearest or entering edge of the port |50 the high pressure gas from the separator 36 then can pass through the conduit 50, the threaded tting |44, the down passage |46, the radial passage |48 to the port passage |50, thence through the slot |52 to the depression l 54 and thence into the compression chamber. This high pressure gas readily flows into the compression chamber since the compression chamber has been filled only with a low pressure gas from the evaporator and substantially no compression thereof has taken place. This gas then iiows into the compression space until the pressure within the-compression space substantially equals the pressure in the high pressure suction conduit 50.

The gas from the suction conduit 5 0 is permitted to ow into the compression chamber until the trailing edge of the slot |52 is no longer through the conduit |66 which connects the sealed unit with the condenser 32.

Second formof compressor In Figs. 13fto 17 thereis shown a modiiied form of the compressor in which a port in the casing feeds the high pressure gas directly to a port in the impeller whichdischarges directly through the periphery of the impeller into the compression chamber. In this form there is provided a cylinderblock 200 containing a slot receiving a divider block 202 pressed inwardly by the compression spring 204 which presses the divider block against an eccentric type impeller 206, which is keyed to a drive shaft. Beneath thecylinder block 200.is a bottom plate 208 and a muiiier 2I0. The low pressure gas enters the compression chamber through the low pressure suction port 2I2 located upon one side of the divider block 202 and the compressed gas is discharged through theI outlet port 2 I4 located upon the opposite side of the divider block in the bot-` ,tom plate. This discharge outlet 2|4 is provided with a check valve andfeeds into the muiiler and thence into the interior of the sealed unit in alike manner as is illustrated in Figs. 2 to 12.

I .v A passage 2|6 is provided for feeding the comin registration with the depression |54. In Fig. 4

the compression chamber for the remainder of the compression stroke no longer has access to the depression |54, the slot |52 or the port |50.

From this point on the compression stroke, the

-`impeller must merely raise the pressure of the refrigerant within the compression chamber to condenser pressure and then expel this gas from the compression chamber through the outlet port |56 located in the bottom plate |I2 adjacent the divider block |32. The outlet port |56 is'provided with a check valve |58 which allows the `compressed gas to ilow into the muiiler |I8 but prevents any gas from flowing from the muilier ||8 back to the outlet port |56. The muiller ||6 includes a series of chambers designated by the reference character |60 which are connected by small apertures |62 located in the dividing` wall between each of the chambers excepting one wall of the chamber which contains the discharge check valve |58.

pressed gas from the muiller to the interior of the sealed unit casing.

Operation of second form of compressor chamber gradually grows in size by the further pressed gas is then removed from the sealed unit `clockwise rotation of the impeller 206 until it takes in the entire' space between the impeller 206 and the cylinder block 200 as shown in Fig.

`13. Further clockwise movement to the position 'shown in Fig. 14 causes the impeller to close the low pressure suction inlet port 2 I2 and begins the compression stroke.

The cylinder block as shown in Fig. 17 is pro- -vided with a threaded high pressure inlet connection 2I8 which is provided for connection with a threaded iltting like that designatedfby the reference character |44 in Fig. 5. The threaded connection 2|8 connects to a downwardly extending passage 220 which at `its lower end connects to the laterally extending passage 222 in the bottom plate 208. This laterally extending passage ends in the port 224 in the upper surface of the bottom plate 208. The impeller 206 is provided with a port 226 adapted to register with the port 224 in the bottom pla'te at a certain portion of eachI revolution of the impeller and this port 226 communicates directly with the compression chamber. When the impeller 206 is in the position shown in Fig. 14 the ports 226 and 224 are not in registration but the low pressure suction inlet port has just been closed and the leading edge of the port 226 is just at the point of extending over one edge of the port 224 and any further movement will permit gas to flow ,from thepassages 220 and 222 into"'the port 226 and from there into the compression chamber.

Further movement in a clockwise dlrectionto the position shown in Fig. 15 will cause the port 226 to move into complete registration with the port 224 thus permitting the free flow of gas from the high pressure suction line into the compression chamber. `Previous to the uncovering of the Compressor propel'.

`the point of leaving the edge of the port 224 thus closing the compressionchamberto the admission of the high pressure suction gas. The reis mainder of the .compression stroke consists in compressing this gas in a compression chamberV and forcing the compressed gas through the outlet port 2|4. This compression stroke is completed when the eccentric reaches the position 20 shown in Fig. 13. This modication therefore is a simplied form of the .compressor as shown in Figs. 2i to 12.

It has been found that in large compressors the rubbing velocitiesbetween the eccentric, the bottom plate, the cylinder block and the upper surface of the compression chamber are relatively high; and even though good lubrication is provided, this high rubbing velocity entails va considerable drag upon the impeller so 'that the no- 3o load power consumption is relatively high. In i order to overcome this relatively high no-load power consumption I have'provided in Figs. 18 to 24 two forms. of compressors in which there is employed a roller type impeller comprising a roll- 3.', cr rotatably mounted upon an eccentric driving member. A l

Third form of compressor.

Referring now to the formshown in Figs. 18` to 20 there Vis provided a cylinder block 302'which m is slotted to receive a divider block 304 pressed\ of the divider block the discharge outlet port 3l6 'is provided. This outlet'port discharges through 50 a check valve (not shown) into a muiiier 3I8 provided beneath the bottom plate 320 of the The cylinder block 302 is provided with a threaded opening 322 for receiving the threaded 55 connection of thehigh pressure suction conduit such as a ttinglike the threaded tting |44 shown in Fig. 5. This threaded opening 322 connects with the downwardly `extending passage A 4`324dwhich at its lower end connects with the 60 laterally extending passage 326 in the bottomV plate 320. This bottom plate 320 'is provided with a high pressure suction port 3 28 which is adapted to be covered by the roller 308 except when the roller is between the positions shownin 65- Figs. 18 and 19. This high pressure suction port begins to uncover when the eccentric and roller impeller moves in a clockwise direction from the position shown in Fig. 18. The port 328 is shown at the point of being uncovered in Fig. 18.

yIt will be seen at `this`time that the gas entering the` compression chamber through* the port 3281.1; this time can flow through the compression chamber until it reaches the low pressure suction inlet port 3l-4, since at this time the 75 ing.

` in Fig. 2,2. when the roller impeller 408 makes the complete roller has not progressed iar' `enough to cover4 the suction inlet port 3|4 or to keep the two inlet ports separated. Therefore I have provided a shoulder at the suction inlet port which supports a light compression spring 330 exerting force against the check valve 332 which seats upon a seat 334 of arubber-like material such as polymerized chloro-Z-butadiene 1,3, commonly called chloroprene rubber. This rubber-like seat 334 is supported by a plug 336 which also serves as a connection fitting for the low pressure suction line. The check valve 332 is provided with prongs at its edge so as to prevent it from seating upon the second shoulderwhich is provided for limiting the opening of the check valve.

As the roller 308 moves from the position shown in Fig. 18 in a; clockwise direction to the position shown in Fig. 19, the port 328 is fully opened and again substantially closedv as shown in Fig. 19. During this movement some compression is taking place and in order to Vprevent the compressing charge of low pressure suction gas and the high pressure suction gas from escaping from the compression chamber through the high pressure suction port 328, I have proi vided a check valve 338 directly beneath the high pressure suction-port 328. This check valve is provided with a seat of chloroprene rubber 340 in an insert-or plug 342 in the bottom' plate 320.

By the use of these two check valves, gas once entering the compression `chamber is prevented from leaving the compression chamber except through the outlet port 3I6.

Fourth form of compressor form there is provided a cylinderrblock 402 which is slotted to receive the divider block 404 pressed inwardly by a light compression spring 40G itO engagement with the periphery of a .roller 408 which is rotatably mounted upon eccentric 4M provided at`the lower end of a drive shaft 412. The remainder of the compressonand sealed unit may be like that shown in Figs. 2 to 12. A suction inlet port 4l4 is provided in the cylinder block 402 adjacent'I the divider block 4 04 and upon the opposite side of the divider block there is provided an outlet port 4 l 6 preferably provided with u `a check valve for controlling the discharge of Operation of fourth ,formof compressor" The suction stroke of the compressor begins with thex roller impeller 408 in the position shown vin Fig'. 21 ,and further movement provides a space boundeaiby theni'vider block, the cylinder block and the portion 'ofv the periphery of the impeller adjacent the low pressure suction inlet port 4I4. Further clockwise movement ofthe roller impeller 408 enlarges this space as is shown by the movement to the position shown This suction stroke is completed revolution and returns to the position shown in Fig. 21.

The cylinder block 402 is provided with a threaded opening 424 for receiving,a threaded tting like that designated by the reference character |44 for connection with the high pressure suction conduit. The threaded opening 424 at its inner end connects with the downwardly extending passage 426 connecting at its lower end with its 'laterally extending passage 428 lin the bottom plate 420. A curved port 430 ls pro- ,vided between about 245 and 280 from thedivider block in the direction of rotation in the upper surface of the bottom plate 420 connecting with the laterally extending passage 428. This curved high pressure suction inlet port 430 is so located that it is just at the point of being uncovered when the roller impeller is at the position shown in Fig. 21. Further clockwise movement of the roller impeller 408 to the position shown in Fig. 23 fully uncovers the curved high pressurel suction inlet port 430 as shown in Fig.

completely fill the portion of the compression chamber in communication with this port at this time. Further clockwise movement of the roller impeller to the position shown in Fig. 22 will again completely cover the high pressure inlet port 430 and permit the remainder of the compression' stroke to proceed in the customary manner so that the gas is brought to compression pressure and expelled through the outlet port M6.

If desired this high pressure suction inlet port 430 may be provided with a check valve like that provided for the high pressure suction inlet port 328 but no check valve is required for the low pressure suction port 4I4 and none is necessary for the high pressure suction port. In this form it is desirable that the low pressure suction port be placed as close as possible to the divider block 404 and it is also desirable that the eccentric 4I!! have as much eccentricity as is possible consistent r with other conditions. This greater amount of eccentricity is desirable in order to proyide more rapid movement and a larger port Thus I have provided an improved form of rei frigerating system with an improved form of multiple effect rotary compressor shown in four different variations. In all these forms a relatively simple eiiicient multiple eiect rotary coinpressor is provided. For certain forms a novel type of oiling system is provided. It is not ne'cessary that these compressors be used with the particular form of system shown in Fig. 1, but the compressor may be used wherever it is desired to compress gas from two different suction pressures todischarge pressure and in an efficient manner. v l l While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

A multiple effect rotary compressor for drawing gas through high and low pressure gas inlets, including an impeller casing provided with spaced parallel piane wall surfaces and a round wall surface extending between the plane wall surfaces, an impeller having surfaces in sealing relation with the spaced walls of the casing, said impeller being provided with a round surface between the parallel surfacesv different in diameter than the round surface of the casing to providea pumping chamber between the impeller and the casing, means for providing a seal transversely across the pumping chamber between one portion of the casing and the impellerto provide a division in the pumping chamber, a low pressure gas inlet and an outlet communicating with the pumping chamber-upon opposite sides of said seal, means for moving the round wall surface of the impeller progressively into sealing relation with successive portions ofthe round wall sur- 

